The present invention relates to digital time-stamping techniques, and more particularly, to a method and apparatus for authenticating time-sensitive interactive communications, such as television events.
The use of public or quasi-public networks, such as the Internet, for transmitting potentially sensitive or proprietary electronic communications, such as electronic mail and electronic financial transactions, is rapidly increasing. Thus, there is a growing need for improved computer security techniques that ensure the privacy or authenticity of such electronic communications. A number of techniques have been proposed or suggested for authorizing or authenticating such electronic messages or the information contained therein, and to ensure that they have not been altered.
For many electronic communications, it is important to verify the time and/or date associated with a message. Thus, techniques have been developed for associating a secure digital time-stamp with an electronic message to validate the reported time and date information. Generally, such digital time-stamps attempt to prevent a user from altering the date of an electronic message, document or transaction. According to one approach, electronic documents are signed and time stamped by an impartial third party, often referred to as a xe2x80x9cdigital notary.xe2x80x9d
In addition, U.S. Pat. No. 5,001,752 to Fischer, incorporated by reference herein, discloses a system for applying a secure time stamp to an electronic document or transaction, without the need for a xe2x80x9cdigital notary.xe2x80x9d For a general discussion of suitable encryption and security techniques, see, for example, B. Schneier, Applied Cryptography (2d ed. 1997), incorporated by reference herein.
While such previous systems for applying a digital time-stamp to electronic documents or transactions have been successful in preventing a user from altering the absolute time or date of the electronic document or transaction, they do not permit the calculation of the differential time it takes for a user to respond to a particular event. Furthermore, such previous systems for applying a digital time-stamp to electronic documents or transactions require very accurate synchronization between the central server and the distributed end-user devices.
Thus, a need exists for a method and apparatus for calculating and validating the time between an event, such as the announcement of an auction or a contest on a television program, and the time at which a user responds. A further need exists for a method and apparatus for calculating and validating the time between an event and the time at which a user responds that provides relaxed synchronization requirements.
Generally, a method and apparatus are disclosed for calculating and validating the differential time between the broadcasting of an event and the time at which a user responds. The event may include, for example, the announcement of an auction or a contest on a television program. For an illustrative television contest embodiment, the present invention determines the time between the initial presentation of the contest to the user and the time when the user responds to the contest.
The present invention permits secure, accurate and real-time multi-user events. The differential time for an end-user response is calculated by the corresponding end-user device. The response, together with the calculated differential response time, can then be reported back to the service provider in a secure and reliable real-time or off-line manner. In one embodiment, each end-user device includes a secure time-keeping device having a secure clock/calendar feature for calculating the differential time between presentation of the event and the user response. The encryption and time-stamping features of the present invention can be incorporated, for example, directly in each end-user device or in a smart card or another portable device that can be inserted into the end-user device.
Another aspect of the invention prevents the fraudulent modification of the differential time. A user is prevented from recording a particular event, for example, using a video cassette recorder (VCR), and thereafter replaying the recorded event and responding to the replayed event, thereby altering the effective response time. Thus, the present invention compares local and global presentation time information to ensure that each user responds to the initial, real-time event and not to a replay.
A more complete understanding of the present invention, as well as further features and advantages of the present invention, will be obtained by reference to the following detailed description and drawings.